Clamshell lathes are known in the art and can be utilized typically in industrial settings to mill a portion of a generally cylindrical pipe or tube. Non-limiting examples of clamshell lathes are disclosed in U.S. Pat. Nos. 4,739,685; 4,939,964; and 5,549,024. Clamshell lathes in some embodiments are designed as annular devices formed from semi-cylindrical halves connected together around a pipe to be milled. A stationary ring of the clamshell lathe is temporarily fixed to the pipe. A rotatable ring is operatively connected to the stationary ring and is rotatable for example by an air, hydraulic, or electrically-operated motor operatively connected to the rotatable ring. In some embodiments, the motor has a motor mount assembly having a housing that is connected to the stationary ring. The motor mount assembly has a drive gear that engages gearing located on the rotatable ring. A tool slide can be mounted on the rotatable ring and is adapted to hold a cutting tool for milling the pipe. The tool slide can include a feed mechanism that advances the tool slide and thus the cutting tool preferably in a radial direction toward the pipe in incremental steps upon a predetermined revolution of the ring gear.
The motor mount assemblies used in the prior art to connect the motor to the lathe are typically connected to the outside diameter of the stationary ring. Such motor mount assemblies have been designed having a plurality of structural arrangements. Some arrangements of motor mount assemblies utilize a drive gear journaled for rotation in the housing that is connected to a drive shaft of the drive motor.
Examples of motor mount assemblies are set forth in the following patents.
U.S. Design Pat. D466,132 relates to an ornamental design for a drive motor mount for a clamshell lathe.
U.S. Pat. No. 4,762,038 relates to a pipe machining apparatus having a tool carrier rotatable about a frame mounted externally of a pipe, with the frame being formed of two semi-annular sections which are releasably held together by connection devices including co-acting pin and latch structures.
U.S. Pat. No. 4,823,655 relates to a multi-speed drive system for a portable lathe, wherein two or more input drive gears are utilized to drive a cutting tool holder ring. Each of the input drive gears has a different pitch diameter so that it will reportedly impart different drive speeds/torque characteristics to the cutting tool holder ring. A main drive gear is interposed between each of the input drive gears and a ring gear attached to the cutting tool holder. The input drive gears are each engaged with the main drive gear and a drive motor is connected to the desired input drive gear.
U.S. Pat. No. 4,939,964 relates to a portable machining lathe having a stationary member interconnected with a gear housing which covers a rotating gear member. A circular race member is connected to the gear member and held in place by means of a plurality of roller bearings. A tool module having a tool bit machines the work piece and automatically advances longitudinally along the work piece by means of an advance mechanism.
U.S. Pat. No. 5,054,342 relates to a pipe machining apparatus that includes a tool carrier with a frame attachable to a pipe for rotatably mounting the tool carrier. The tool carrier is circumferentially rotatable about the pipe and carries a tool for performing cutting or machining operations on the pipe. A plurality of rotatable bearings are provided between the frame and the tool carrier, and the bearings are reportedly individually adjustable in a radial direction to compensate for wear of the bearings during use of the apparatus.
U.S. Pat. No. 5,549,024 relates to a clamshell machining lathe for cutting and finishing pipes in industrial settings comprising a split-ring assembly, including a clamping ring that is positioned about the pipe, and journaled to the clamping ring is a rotatable gear ring that supports a tool block carrying a cutting tool.
U.S. Pat. No. 6,427,567 relates to a motor mount for attaching a drive motor to a clamshell lathe including a gear box whose angular disposition reportedly can be adjusted relative to a drive gear housing affixed to the periphery of the clamshell lathe. This reportedly facilitates the positioning of the clamshell lathe on a workpiece with reduced chance of interference of the drive motor with neighboring obstructions.